1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a backlight module and a liquid crystal display device using the backlight module.
2. The Related Arts
Liquid crystal displays have a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and are thus widely used. Most of the liquid crystal displays that are currently available in the market are backlighting liquid crystal displays, which comprise a liquid crystal display panel and a backlight module. The operation principle of the liquid crystal display panel is that, with liquid crystal molecules interposed between two parallel glass substrates, a number of tiny vertical and horizontal electrical wires are arranged between the two glass substrates to selectively receive application of electricity thereto to control the rotation direction of the liquid crystal molecules in order to refract out light emitting from the backlight module for generating images. Since the liquid crystal display panel itself does not emit light, light must be provided by the backlight module in order to normally display images. Thus, the backlight module is one of the key components of a liquid crystal display. The backlight modules can be classified in two types, namely a side-edge backlight module and a direct backlight module, according to the position where light gets incident. The direct backlight module comprises a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), which is arranged at the backside of the liquid crystal display panel to form a planar light source directly supplied to the liquid crystal display panel. The side-edge backlight module comprises an LED light bar, serving as a backlight source, which is arranged at an edge of a backplane to be located rearward of one side of the liquid crystal panel. The LED light bar emits light that enters a light guide plate (LGP) through a light incident face at one side of the light guide plate and is projected out of a light emergence face of the light guide plate, after being reflected and diffused, to pass through an optic film assembly to form a planar light source for the liquid crystal panel.
Thinning is the current trend of development of the liquid crystal display devices. Referring to FIG. 1, a schematic view is given to show the structure of a conventional thinned liquid crystal display device, which comprises: a backlight source 100, a mold frame 300 arranged on the backlight module 100, and a liquid crystal display panel 500 arranged on the mold frame 300. The backlight source 100 comprises: a backplane 102, a light guide plate 104 arranged in the backplane 102, a backlight source 106 arranged in the light guide plate 104, and a reflector plate 108 arranged between a bottom plate 122 of the backplane 102 and the light guide plate 104. The light guide plate 104 is directly positioned on the reflector plate 108. The light guide plate 104 has a bottom surface 142 that forms no gap with respect to the reflector plate 108 in order to reduce the thickness of the liquid crystal display device for realizing thinning of the liquid crystal display device.
However, when the surface of the bottom plate 122 of the backplane 102 that faces the reflector plate 108 is not sufficiently smooth (such as having raised portions), the reflector plate 108 would be raised up thereby increasing friction between the reflector plate 108 and the light guide plate 104 and thus readily leading to damage of the light guide plate 104.